Filter paper for oil filters

ABSTRACT

A filter paper for oil filters has a coarse web capable of passing particles of granular size of about 40 Mu maximum diameter and a plurality of dense web strips superposed in parallel upon the coarse web and combined therewith at fixed intervals, the dense web being capable of passing particles of granular size of about 15 Mu maximum diameter.

Umted States Patent 1151 3,640,839 Ochiai Feb. 8, 1972 [54] FILTER PAPERFOR OIL FILTERS [56] References Cited [72] Inventor: Tuguo Ochiai,Kanagawa, Japan UNITED STATES PATENTS 1 Assignw Tokyo Roki KabushikiKaisha, Kanagawa, 2,675,127 4/1954 Layte ..21o/4s9 x Japan 3,322,6175/1967 Osborne ..i62/296 [22] Filed: Sept 1968 Primary Examiner-S. LeonBashore [21] Appi. No.: 767,547 Assistant Examiner-Richard H. TushinAttorney-Richards & Geier [30] Foreign Application Priority Data [57]ABSTRACT July 3, Japan A filter p p for filters has a coarse web capablef p g particles of granular size of about 40 p. maximum diameter 52 us.(:1 ..l62ll29, 162/133, 162/304, and a plurality of dense web Stripssuperposed in parallel upon 210/491 the coarse web and combinedtherewith at fixed intervals, the [51] Int. Cl ..B07b 11/04, D21f 1 1/08dense web being capable of passing particles f granular Size [58] Fieldof Search 210/489, 490, 491, 498; of about 15 p, maximum diameten 2Claims, 8 Drawing Figures Pmmrsnm 3.640.839

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SHEET 2 OF 2 INVENTOR: Oc/u'aL' giiwwbrfiw -r-romN E55 FILTER PAPER sonon. FILTERS BACKGROUND OF THE INVENTION This invention relates to filterpapers for oil filters and refers more particularly to filter papers andadaptable for the filtering system of the full-flow type.

In general, oil filters should have simultaneously a cleansing function,by which sludges in lubrication oil will be removed, and a screeningfunction, by which contaminants resulting from the wear and tear of thesliding parts of a machine will be removed. For this purpose it isconventional to use a pleattype dense filter paper as a filter elementfor full-flow filtering. In the pleat type a wider filter area resultsin small pressure losses while in use, and its pore size is relativelyeasy to control. On the other hand, this filter paper has the drawbackthat, when it is dense and homogeneous enough to remove minute particlesin the oil, its pores are easily closed by the particles so that theservice life of the filter paper is a short one.

Recently, there has been provided a combination of a pleattype filterpaper, which has high filtering efficiency, with an insert of depth typein which synthetic fibers are combined with a binder, for use as afilter element for full-flow filtering, but difficulties wereencountered in manufacturing and constructing it.

Furthermore, two kinds of filters are known, namely a bypass filterthrough which oil is directly retumed to an oil pan and a full-fiow-typefilter through which all of the oil to be sent to the bearing is passed.This combination filter is used for heavy-duty engines, but it is not ingeneral use due to the restriction of space in which it must be fittedand for economic reasons.

SUMMARY OFTHE INVENTION An object of the present invention is to providea filter paper having cleansing and screening functions and,simultaneously, an extended service life.

Another object of the present invention is to provide a filter paper ofexcellent filtering efiiciency and extended service life.

A further object of the present invention is to provide a filter paperwhich will not be torn off when it is bent by a pleat machine.

Other objects of the present invention will become apparent in thecourse of the following specification.

In the accomplishment of the objectives of the present invention it wasfound desirable to provide a filter paper for oil filters comprising acoarse web capable of passing particles of granular size of about 40p.maximum diameter and a plurality of dense web strips superposed inparallel upon the coarse web and combined therewith at fixed intervals,the dense web being capable of passing particles of granular size ofabout 15p. maximum diameter.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawings,showing by way of example, preferred embodiments of the inventive idea.

In the drawings:

FIGS. 1, 2, 3 and 4 are partial perspective views of filter papers ofdifferent structures made according to the present invention;

FIG. 5 is a diagrammatic side view of an apparatus for making a filterpaper of the present invention;

FIG. 6 is a vertical section along the line VIVI in FIG. 5;

FIG. 7 is a diagrammatic side view of a somewhat different apparatus formaking a filter paper;

FIG. 8 is a vertical section along the line VHIVIII in FIG. 7.

FIGS. 1 to 4 show filter papers 10, 10a, 10b and )0, respectively, whichare made by superposing relatively dense wet webs 30 upon relativelycoarse wet webs and combining them by pasting or the like. The filterpaper is so constructed that it comprises, as a vertical sectioned view,double layer parts in which a dense web is superposed upon a coarse web.Some filters may also have single layer parts of a coarse web.

Preferably, the granular sizes capable of passing through the coarse weband the dense web are a maximum of about 40a diameter and 15;:- diameterrespectively, as compared to a maximum of about 25 diameter forconventional filter paper.

The fiber mixing proportion of the coarse web is.by weight from 40 to 60percent of cotton fiber and from 60 to 40 percent of rayon (from 1.5 to7 denier thick and from 5 to 10 mm. staple length), while the dense webconsists of percent cotton fibers.

When oil which is being filtrated is circulating through this filterpaper, the double layer parts will carry out the cleansing function sothat minute particles in oil will be removed, while the single layerparts will carry out the screening function so that particles which mayhave bad influence on the wear of the machine will be removed.

When the double layer parts are closed by dust and dirt, the singlelayer parts will also become closed by them, so that not only thefiltering function will not be lowered as a whole, but also thecleansing efficiency for oil will be raised compared with that at thebeginning of use. Furthermore, with this construction, the service lifeof the filter paper will also be extended. The plane of the dense webmay be of any shape.

In the example shown in FIG. 1, the layer of dense web is arranged inparallel longitudinal stripes.

In the example shown in FIG. 2, very thin dense web parts 32 extendbetween thick dense web stripes 31 and upon the coarse web 20.

In the examples shown in FIGS. 3 and 4, the dense web 30 is regularlypunched forming holes 33. The construction of FIG. 4 has an additionalvery thin dense web layer 32.

The ratio of planar exposed surface area of a plurality of dense webs tothat of exposed coarse web is in the range of 10:5 to 10:10. If stressis laid upon the filtering efficiency of the filter paper, the desirableratio is 10:6. If greater value is placed on the service life, the ratioshould be 10:10.

In the constructions shown in FIGS. 2 and 4, relatively thick dense webparts are connected with the very thin dense web parts 32 and all denseweb parts are combined by being pasted upon the coarse web 20.Therefore, the filter paper of these constructions will hardly be tornoff even if the filter is bent by the pleat machine. Furthermore, thestrength of the filter is increased by these structures. In order tokeep high degree of filtration for oil, the thickness of the web parts32 should be as small as possible.

When a filter element is constructed by applying this filter paper, itis important that the filter paper should be so arranged that oil mayflow through from the side of the coarse web 20.

If oil flows through the filter paper from the dense web side the minuteparticles which may not be removed by the dense web can no longer beremoved by the coarse web 20 and thus the coarse web will be of no use.

In order to make not only the coarse web but also the dense web for thefilter paper of this invention by the use of known paper machines, suchas the Fourdrinier machine 50 (FIG. 5) or cylinder machine 60 (FIG. 7),in accordance with the present invention, flexible covers are applied onthe surface of the moving endless belt of wire cloth (the Fourdrinierwire) or on the surface of the wire-covered cylinder or mold, by whichwet dense web is made, so that the mesh of the wire may be closedpartially by the covers. As the flexible cover, for example, an adhesivesheet, a narrow steel plate or the like can be used. These covers arefitted on the moving belt or cylinder in rows at fixed intervals. Alsothe surface of the wire may be covered with a cloth upon which holes areregularly formed.

In operation, when fiber-water mixture is supplied to the wire so thatthe surface of the liquid will be above the upper surface of the covers,a relatively thick web 31 is provided between the covers, and on thecontrary a very thin web 32 is provided upon each cover. Therefore, inaccordance with this method, it is very easy to connect the relativelythick web parts 31 with the very thin web parts 32. When the fiber-watermixture is supplied to the wire so that the liquid surface thereof isbelow the surface of the covers, a relatively thick web 30 only isprovided separately between the covers thus providing a plurality ofparallel strips 30 shown in FIG. 1.

Instead of placing flexible covers on the surface of the wire to closethe wire meshes, a comb-teeth-shaped guiding plate 62 (FIG. 7) may beprovided opposite a cylindrical forming roll 61 with the spaces or slotsof the plate facing the roll so that paper is formed therein.

Moreover, in order to provide two different wide and narrow spacesbetween the surface of the Fourdrinier wire or wire-covered mold and aguiding plate, the guiding plate for the fiber-water mixture having asurface with rectangular projections is fixed opposite the Fourdrinierwire or wire-covered mold, so that the fiber-water mixture may flowbetween the spaces.

The wet dense web made in accordance with the above method is combinedwith the coarse web to make a filter paper of the present invention.

In accordance with the procedure illustrated in FIGS. 5 and 6, afiber-water mixture, which is the starting material, is used in whichthe fiber mixing proportion is 50 percent of cotton fiber and 50 percentof rayon fiber. This mixture is applied to the paper making machine 40and the wet web 20, through which the granules of a maximum 40 diametermay pass, is made in accordance with the conventional method.

The fiber-water mixture wherein the fiber is 100 percent cotton isapplied to another paper-making machine 50 having a plurality of thinsteel plates 52 which are 6 mm. wide and spaced to the extent of 10 mm.These plates are fitted in the lengthwise direction around the wire mesh51 so that a wet web 30, through which granules of a maximum diameter ofp. may pass, is made.

The wet web 30 made by arranging the liquid surface of the fiber-watermixture is combined with the other web attached to and carried by woolenfabric or felt 41 so that the filter paper is made.

Instead of the thin steel plates 52, a cloth having regularly arrangedholes of 5 mm. diameter forming squares of 10 mm. may cover the surfaceof the endless wire. In the same process as described above, the denseweb 30 made by the liquid surface of the fiber-water mixture is combinedwith the coarse web 20 to make a filter paper shown in FIGS. 3 and 4.

In the embodiment shown in FIGS. 7 and 8, wet web 30 is made by using acylinder machine 60 in which a guiding plate 62 is fixed opposite to thecylindrical wire 61 for paper making. Thesurface of the guiding plate 62opposite to the cylindrical wire 61 is provided with regularly arrangedlongitudinal rectangular portions 63. The fiber-water mixture issupplied to the narrow and wide spaces between the cylindrical wire andthe guiding plate to make a web. Otherwise this process is the same asthe one previously described. When the structure of FIG. 7 produces adense web having strips such as 31 and thin dense web parts such as 32thethin web is separated from the coarse web by the strips.

While there have been described herein what are at present consideredpreferred embodiments of the invention, it will be obvious to thoseskilled in the art that many modifications and changes may be madetherein without departing from the essence of the invention. It istherefore to be understood that the exemplary embodiments areillustrative and not restrictive of the invention, the scope of which isdefined in the appended claims, and that all modifications that comewithin the meaning and range of equivalency of the claims are includedtherein.

What is claimed is:

1. A filter paper for oil filters, consisting of coarse web made mainlyof cotton fiber and rayon, said coarse web being able to be passed byparticles of granular size about 40p. in maximum diameter, and aplurality of dense web strips made mainly of cotton fiber and joined inparallel to said coarse web at fixed intervals, said dense web stripsbeing able to be passed by 2particles of granular size about 15 y. inmaximum diameter.

. A filter paper 1n accordance with claim 1, wherein the

2. A filter paper in accordance with claim 1, wherein the ratio ofplanar exposed surface area of the plurality of dense web strips to thatof coarse web is in the range of 10:5 to 10:10.